Fuzzy logic-based downlink subchannel allocation for capacity maximization in OFDMA femtocells

In this paper, we propose a fuzzy logic-based dynamic subchannel allocation scheme for densely deployed femtocell networks affected by strong co-tier interference. The channel model includes Rayleigh fading with path loss and the femtocells use OFDMA-based channel access. The reported signal-to-interference plus noise ratio (SINR) values at femtocell base stations are used to form a fuzzy superset, which in turn is utilized to allocate subchannels in an optimal way. The results are compared with the traditional user-oriented and channel-oriented subchannel allocation schemes. The proposed scheme provides almost the same system capacity with better fairness as compared to traditional channel-oriented scheme, while it also improves the sum-rate capacity of the femtocell network as compared to the user-oriented scheme. Simulations have been performed to judge the quality of proposed algorithm for a variety of densely deployed femtocells.